diff --git a/Crypto/Random/AESCtr.hs b/Crypto/Random/AESCtr.hs
--- a/Crypto/Random/AESCtr.hs
+++ b/Crypto/Random/AESCtr.hs
@@ -22,7 +22,11 @@
 
 import Control.Applicative ((<$>))
 
-import Crypto.Random
+#ifdef USE_CRYPTOAPI
+import qualified Crypto.Random as CAPI
+#endif
+import Crypto.Random.API
+
 import System.Random (RandomGen(..))
 import System.Entropy (getEntropy)
 #ifdef CIPHER_AES
@@ -34,6 +38,7 @@
 import Data.ByteString (ByteString)
 import qualified Data.ByteString as B
 
+import Data.Maybe (fromJust)
 import Data.Word
 import Data.Bits (xor, (.&.))
 
@@ -52,6 +57,7 @@
 data RNG = RNG
     {-# UNPACK #-} !Word128
     {-# UNPACK #-} !Word128
+    {-# UNPACK #-} !Word64
     {-# UNPACK #-} !AES.Key
 
 data AESRNG = AESRNG { aesrngState :: RNG
@@ -112,12 +118,12 @@
 -- the initialization.
 --
 -- use `makeSystem` to not have to deal with the generator seed.
-make :: B.ByteString -> Either GenError AESRNG
+make :: B.ByteString -> Maybe AESRNG
 make b
-    | B.length b < 64 = Left NotEnoughEntropy
-    | otherwise       = Right $ AESRNG { aesrngState = rng, aesrngCache = B.empty }
+    | B.length b < 64 = Nothing
+    | otherwise       = Just $ AESRNG { aesrngState = rng, aesrngCache = B.empty }
         where
-            rng            = RNG (get128 iv) (get128 cnt) key
+            rng            = RNG (get128 iv) (get128 cnt) 0 key
             (key, cnt, iv) = makeParams b
 
 #ifdef CIPHER_AES
@@ -125,9 +131,9 @@
 chunkSize = 1024
 
 genNextChunk :: RNG -> (ByteString, RNG)
-genNextChunk (RNG iv counter key) = (chunk, newrng)
+genNextChunk (RNG iv counter sz key) = (chunk, newrng)
     where
-        newrng = RNG (get128 chunk) (add64 counter) key
+        newrng = RNG (get128 chunk) (add64 counter) (sz+fromIntegral chunkSize) key
         chunk  = AES.genCTR key (AES.IV bytes) 1024
         bytes  = put128 (iv `xor128` counter)
 #else
@@ -135,19 +141,22 @@
 chunkSize = 16
 
 genNextChunk :: RNG -> (ByteString, RNG)
-genNextChunk (RNG iv counter key) = (chunk, newrng)
+genNextChunk (RNG iv counter sz key) = (chunk, newrng)
     where
-        newrng = RNG (get128 chunk) (add1 counter) key
+        newrng = RNG (get128 chunk) (add1 counter) (sz+fromIntegral chunkSize) key
         chunk  = AES.encrypt key bytes
         bytes  = put128 (iv `xor128` counter)
 #endif
 
+getRNGReseedLimit :: RNG -> Int
+getRNGReseedLimit (RNG _ _ sz _)
+    | sz >= limit = 0
+    | otherwise   = fromIntegral (limit - sz)
+    where limit = 2^(24 :: Int)
+
 -- | Initialize a new AES RNG using the system entropy.
 makeSystem :: IO AESRNG
-makeSystem = ofRight . make <$> getEntropy 64
-    where
-        ofRight (Left _)  = error "ofRight on a Left value"
-        ofRight (Right x) = x
+makeSystem = fromJust . make <$> getEntropy 64
 
 -- | get a Random number of bytes from the RNG.
 -- it generate randomness by block of chunkSize bytes and will returns
@@ -163,8 +172,8 @@
             | otherwise          = let (b, g') = genNextChunk g
                                     in acc (l+1) (b:bs) g'
 
-genRandomBytes :: AESRNG -> Int -> (ByteString, AESRNG)
-genRandomBytes rng n
+genRanBytes :: AESRNG -> Int -> (ByteString, AESRNG)
+genRanBytes rng n
     | B.length (aesrngCache rng) >= n = let (b1,b2) = B.splitAt n (aesrngCache rng)
                                          in (b1, rng { aesrngCache = b2 })
     | otherwise                       =
@@ -172,27 +181,36 @@
                 (b1, b2)  = B.splitAt n b
              in (b1, rng { aesrngState = rng', aesrngCache = b2 })
 
-reseedState b rng@(RNG _ cnt1 _) = RNG (get128 r16 `xor128` get128 iv2) (cnt1 `xor128` get128 cnt2) key2
+reseedState :: ByteString -> RNG -> RNG
+reseedState b rng@(RNG _ cnt1 _ _) = RNG (get128 r16 `xor128` get128 iv2) (cnt1 `xor128` get128 cnt2) 0 key2
     where (r16, _)          = genNextChunk rng
           (key2, cnt2, iv2) = makeParams b
 
-instance CryptoRandomGen AESRNG where
-    newGen           = make
+#ifdef USE_CRYPTOAPI
+-- going away in 0.4.0. use the CPRG instance.
+instance CAPI.CryptoRandomGen AESRNG where
+    newGen b         = maybe (Left CAPI.NotEnoughEntropy) Right $ make b
     genSeedLength    = 64
-    genBytes len rng = Right $ genRandomBytes rng len
+    genBytes len rng = Right $ genRanBytes rng len
     reseed b rng
-        | B.length b < 64 = Left NotEnoughEntropy
+        | B.length b < 64 = Left CAPI.NotEnoughEntropy
         | otherwise       = Right $ rng { aesrngState = reseedState b (aesrngState rng) }
+#endif
 
+instance CPRG AESRNG where
+    cprgGenBytes rng len          = genRanBytes rng len
+    cprgSupplyEntropy rng entropy = rng { aesrngState = reseedState entropy (aesrngState rng) }
+    cprgNeedReseed rng            = getRNGReseedLimit (aesrngState rng)
+
 instance RandomGen AESRNG where
     next rng =
-        let (bs, rng') = genRandomBytes rng 16 in
+        let (bs, rng') = genRanBytes rng 16 in
         let (Word128 a _) = get128 bs in
         let n = fromIntegral (a .&. 0x7fffffff) in
         (n, rng')
     split rng =
-        let (bs, rng') = genRandomBytes rng 64 in
+        let (bs, rng') = genRanBytes rng 64 in
         case make bs of
-            Left _      -> error "assert"
-            Right rng'' -> (rng', rng'')
+            Nothing    -> error "assert"
+            Just rng'' -> (rng', rng'')
     genRange _ = (0, 0x7fffffff)
diff --git a/cprng-aes.cabal b/cprng-aes.cabal
--- a/cprng-aes.cabal
+++ b/cprng-aes.cabal
@@ -1,5 +1,5 @@
 Name:                cprng-aes
-Version:             0.2.5
+Version:             0.3.0
 Description:         
     Simple crypto pseudo-random-number-generator with really good randomness property.
     .
@@ -38,11 +38,15 @@
   Description:       Use cereal
   Default:           False
 
+Flag cryptoapi
+  Description:       Use cereal
+  Default:           True
+
 Library
   Build-Depends:     base >= 3 && < 5
                    , bytestring
                    , random
-                   , crypto-api >= 0.8
+                   , crypto-random-api
                    , entropy >= 0.2
   Exposed-modules:   Crypto.Random.AESCtr
   ghc-options:       -Wall
@@ -54,6 +58,10 @@
     Build-Depends:   cryptocipher
   if flag(cereal)
     Build-Depends:   cereal >= 0.3.0 && < 0.4.0
+    cpp-options:     -DUSE_CEREAL
+  if flag(cryptoapi)
+    Build-Depends:   crypto-api >= 0.8
+    cpp-options:     -DUSE_CRYPTOAPI
 
 Benchmark bench-cprng-aes
   hs-source-dirs:    Benchmarks